Speedr has a speedometer showing you your current driving speed and the speed limit of the road. Anytime you drive faster than the speed limit Speedr uses the speedometer to calculate how much time the extra speed is saving. Your total drive time is shown along with an 'estimated drive time if you were not speeding'.

Speedr shows how much time or how little time you save when speeding in your car or motorcycle. Discover if speeding is really worth the safety risks risks of speeding tickets and increased gas consumption by measuring how much time you really save.

Speedr has the ability to run in the background of your phone or tablet so that you can use navigation apps like Google Maps at the same time.

Speed limit data is provided by OpenStreetMap and HERE Maps navigation services. If you discover while driving your vehicle that your area does not have speed limit coverage you can edit OpenStreetMap at openstreetmap.org. Since the speed limit data may not always be accurate be sure to pay attention to your vehicle's speedometer at all times.

Source code here: https://github.com/jakehilborn/speedr